Peelable clay/PE nanocomposite seals with ultra-wide peelable heat seal temperature window

摘要

This study shows that the controlled dispersion and distribution of nanoclay in clay/polyethylene (PE) nano composites result in peelable sealants with an ultra-wide peelable heat-seal temperature window (Delta T-p). Different nanoclays, unmodified montmorillonite (Mt) and organo-modified Mt. (OMt), were examined for their capacity to generate peelable clay/PE nanocomposites in a melt-blending film extrusion process. Clay/PE nanocomposite films containing 6 mass% organoclay (OC) exhibited a cohesive peel behavior with a Delta T-p of about 12 degrees C while PE film containing 6 mass% unmodified clay resulted in microcomposite with a lock seal performance. With the same mass% of OC, a much lower peel strength with a significantly broad Delta T-p, of 45 degrees C was achieved mainly due to the fine dispersion of OMt when PE-grafted-maleic anhydride (PE-g-MA) was used as a compatibilizer. WAXD and TEM results confirmed that a substantial enhancement in the dispersion and distribution of intercalated nanoclays was achieved with PE-g-MA compatibilizer. Finally, an ultra-wide Delta T-p of over 100 degrees C was obtained for compatibilized OC/PE nanocomposite sealant containing only 3 wt% OC with partially exfoliated microstructure indicating that the exfoliation of nanoclay is in favor of peelability. The peel fracture mechanics of the clay/PE nanocomposite sealants were examined through T-peel test and SEM imaging. The results showed that the dispersion and distribution of nanoclay along with the interfacial adhesion between nanoclay and matrix are the key factors controlling the peel performance of the sealants.